The invention relates to the repair of mitral and tricuspid valves exhibiting valve regurgitation. More particularly, the invention relates to apparatus and methods suitable for a less invasive repair of a mitral or tricuspid heart valve.
Mitral regurgitation, i.e., backward leakage of blood at the mitral heart valve, results in reduced pumping efficiency. Furthermore, compensatory mechanisms such as hypertrophy and dilation of the ventricle suggest early treatment to prevent progressive deterioration of ventricular function. Diagnosis of mitral regurgitation can be performed using visualization with transesophageal echocardiography or by echocardiography. In particular, defective leaflet coaptation and the site and direction of the regurgitant flow can be examined to evaluate likely modes of failure.
Mitral valve prolapse, i.e., myxomatous degeneration of mitral valve leaflets, is the most common cause of mitral regurgitation in North America. Rheumatic heart disease was the most common cause of mitral regurgitation in the U.S.A. thirty years ago and is still the most common cause of mitral regurgitation in developing countries. Chronic rheumatic heart disease results in retraction, deformity and rigidity of one or both mitral valve cusps as well as structural abnormalities in the commissures, chordae tendinae and papillary muscles. Ischemic mitral regurgitation (IMR), i.e., anemia of the valve tissue due to reduced arterial blood flow feeding the valve tissue, is the second most common cause of mitral valve regurgitation. Studies suggest that annular irregularities and posterior papillary muscle fibrosis with scarring of the underlying ventricular wall may be associated with IMR.
Many cases of mitral regurgitation can be repaired by modifications of the original valve in a procedure generally referred to as valvuloplasty. These repair procedures typically involve a full sternotomy and quadrangular resection of the anterior leaflet, while on cardiopulmonary bypass. Repairs can also involve reattachment of chordae tendinae, which tether the valve leaflets, or removal of leaflet tissue to correct misshapen or enlarged valve leaflets. In some cases, the base of the valve is secured using an annuloplasty ring. Valves that are heavily calcified or significantly compromised by disease may need to be replaced.
As an alternative to these repair techniques, an edge-to-edge suturing of the anterior and posterior mitral valve leaflets can be performed. Commonly referred to as a "bow-tie" repair, edge-to-edge suturing ensures leaflet coaptation without performing a quadrangular resection of the anterior leaflet. The bow-tie repair generally involves the use of a centrally located suture, although a suture can be placed close to a commissure, or multiple sutures can be used to complete the repair. A centrally placed suture creates a double orifice valve, which resembles a bow-tie.
The bow-tie repair procedure has been applied using invasive procedures by placing the patient on extracorporeal circulation. An incision is made to provide access into the left atrium of the heart. Following suturing, the atrium is closed. Such repairs can result in a significant decrease in mitral regurgitation along with a corresponding increase in the ejection fraction.